Buggy code:
public class RegexExtractor extends AbstractScopedTestElement implements Serializable , PostProcessor { private static final long serialVersionUID = 240L ; private static final Logger log = LoggingManager . getLoggerForClass ( ) ; private static final String MATCH_AGAINST = "RegexExtractor.useHeaders" ; public static final String USE_HDRS = "true" ; public static final String USE_BODY = "false" ; public static final String USE_BODY_UNESCAPED = "unescaped" ; public static final String USE_BODY_AS_DOCUMENT = "as_document" ; public static final String USE_URL = "URL" ; public static final String USE_CODE = "code" ; public static final String USE_MESSAGE = "message" ; private static final String REGEX = "RegexExtractor.regex" ; private static final String REFNAME = "RegexExtractor.refname" ; private static final String MATCH_NUMBER = "RegexExtractor.match_number" ; private static final String DEFAULT = "RegexExtractor.default" ; private static final String TEMPLATE = "RegexExtractor.template" ; private static final String REF_MATCH_NR = "_matchNr" ; private static final String UNDERSCORE = "_" ; private transient List < Object > template ; @ Override public void process ( ) { } private String getInputString ( SampleResult result ) { } private List < MatchResult > processMatches ( Pattern pattern , String regex , SampleResult result , int matchNumber , JMeterVariables vars ) { if ( RegexExtractor . log . isDebugEnabled ( ) ) { RegexExtractor . log . debug ( ( "Regex<seq2seq4repair_space>=<seq2seq4repair_space>" + regex ) ) ; } Perl5Matcher matcher = JMeterUtils . getMatcher ( ) ; List < MatchResult > matches = new ArrayList < MatchResult > ( ) ; int found = 0 ; if ( isScopeVariable ( ) ) { String inputString = vars . get ( getVariableName ( ) ) ; if ( inputString == null ) { <START_BUG> RegexExtractor . log . warn ( ( ( ( ( "No<seq2seq4repair_space>variable<seq2seq4repair_space>'" + ( getVariableName ( ) ) ) + "'<seq2seq4repair_space>found<seq2seq4repair_space>to<seq2seq4repair_space>process<seq2seq4repair_space>by<seq2seq4repair_space>RegexExtractor<seq2seq4repair_space>" ) + ( getName ( ) ) ) + ",<seq2seq4repair_space>skipping<seq2seq4repair_space>processing" ) ) ; <END_BUG> return Collections . emptyList ( ) ; } matchStrings ( matchNumber , matcher , pattern , matches , found , inputString ) ; } else { List < SampleResult > sampleList = getSampleList ( result ) ; for ( SampleResult sr : sampleList ) { String inputString = getInputString ( sr ) ; found = matchStrings ( matchNumber , matcher , pattern , matches , found , inputString ) ; if ( ( matchNumber > 0 ) && ( found == matchNumber ) ) { break ; } } } return matches ; } private int matchStrings ( int matchNumber , Perl5Matcher matcher , Pattern pattern , List < MatchResult > matches , int found , String inputString ) { } private void saveGroups ( JMeterVariables vars , String basename , MatchResult match ) { } private void removeGroups ( JMeterVariables vars , String basename ) { } private String generateResult ( MatchResult match ) { } private void initTemplate ( ) { } private MatchResult getCorrectMatch ( List < MatchResult > matches , int entry ) { } public void setRegex ( String regex ) { } public String getRegex ( ) { } public void setRefName ( String refName ) { } public String getRefName ( ) { } public void setMatchNumber ( int matchNumber ) { } public void setMatchNumber ( String matchNumber ) { } public int getMatchNumber ( ) { } public String getMatchNumberAsString ( ) { } public void setDefaultValue ( String defaultValue ) { } public String getDefaultValue ( ) { } public void setTemplate ( String template ) { } public String getTemplate ( ) { } public boolean useHeaders ( ) { } public boolean useBody ( ) { } public boolean useUnescapedBody ( ) { } public boolean useBodyAsDocument ( ) { } public boolean useUrl ( ) { } public boolean useCode ( ) { } public boolean useMessage ( ) { } public void setUseField ( String actionCommand ) { } }

Fix:
RegexExtractor . log . warn ( ( ( ( ( "No<seq2seq4repair_space>variable<seq2seq4repair_space>'" + ( getVariableName ( ) ) ) + "'<seq2seq4repair_space>found<seq2seq4repair_space>to<seq2seq4repair_space>process<seq2seq4repair_space>by<seq2seq4repair_space>RegexExtractor<seq2seq4repair_space>'" ) + ( getName ( ) ) ) + "',<seq2seq4repair_space>skipping<seq2seq4repair_space>processing" ) ) ;